1. Field of Invention
The present invention relates generally to data and telecom communication systems. More particularly, the present invention relates to systems and methods for providing a multi-port line card which is capable of enabling multiple signal or line rates of different protocols to be efficiently supported.
2. Description of the Related Art
The demand for data and telecom communication services is growing at an explosive rate. Much of the increased demand is due to the fact that as the use of computing devices becomes more prevalent, the need for creating networks of computing devices such that resources may be shared between the computing devices also increases. Computing devices often share transmission bandwidth with legacy voice and video services more common to the telecommunications industry. The implementation and operation of a network is preferably such that resources from both environments may be shared in an efficient manner. As a result, the ability to handle different line rates and protocols and the ability to increase the bandwidth of signals is becoming more important.
A Multiservice Provisioning Platform (MSSP) is an example of optical transport equipment which may be used in a metropolitan network and offers TDM and SONET services, as well as Ethernet service interfaces, in a platform that is relatively small, e.g., smaller than conventional, or legacy, SONET add-drop multiplexer and digital cross connect equipment. An MSSP generally provides an increased amount of scalability and functionality over than provided by conventional SONET equipment, while requiring less space than conventional SONET equipment, and is relatively cost effective. In addition, an MSSP enables the bandwidth handled on networks to be increased, and also combines the functions of legacy SONET ADMs and cross-connects into a single platform.
In order to support numerous high-speed metropolitan rings, an MSSP generally has a high port density. Hence, line cards used in a system which may be part of an MSSP are becoming multi-port line cards. Fixed rate multi-port line cards, or line cards with multiple ports which support signals of a fixed rate, are often used in an MSSP or on a large broadband digital cross connects (BBDXC). While effective in supporting signals of a fixed rate, the use of fixed rate multi-port line cards typically limits the ability of service providers to react to service demands at varying line rates, as the service providers may have to overbuy fixed rate multi-port line cards across all potential fixed rates. For example, if one customer has been sending OC-3 signals and now wishes to send OC-48 signals, a service provider may need to obtain a new multi-port line card to support the OC-48 signals.
The need to obtain separate fixed rate multi-port line cards to allow signals of different rates to be supported by a system leads to a lack of flexibility when the system is scaled, and also leads to an increased probability that all line card slots in the system may be filled beyond system expansion limits before a full service density is achieved. In order to increase the flexibility of a system, some multi-port line cards allow for some rate variation. Such multi-rate, multi-port line cards may support two or three different signal rates of the same protocol. Each port of such line cards may be provisionable to support different rates. By way of example, a multi-rate, multi-port line card may support both OC-3 and OC-12 signals. Although the use of multi-rate, multi-port line cards may slightly increase the bandwidth and the flexibility of a system, since only a relatively small variation in line rates is supported, the increase in flexibility is generally not significant in terms of reducing the probability that all line card slots within a system will fill beyond system expansion limits without achieving a full service density. Further, such multi-rate, multi-port line cards generally support only a single protocol.
Therefore, the functionalities needed are a method and an apparatus which allow different line rates to be efficiently supported within a system such as an MSSP or a BBDXC. That is, what is desired is a line card which allows multiple, varied rates of different protocols and optical span reaches to be supported on different ports such that a service density and flexibility associated with a system which uses the line card may be significantly increased. This next generation line card should be flexible to the extent that increasing bandwidth or migrating from SONET to Ethernet services may be provisioned through software without hardware changes including optics modules.